An inter-network mutual connecting system is known. In the inter-network mutual connecting system, nodes are included in a network in which a connection port of a communication apparatus is recognized from a message which the communication apparatus sends, and routing is controlled. A node of the network includes storing means for storing transmission destination address information, transmission source address information, reception input and output port information and final access time information of a message which passes through the node, accessing means for accessing the storing means and transmission/reception control means for controlling transmission/reception of the message. In the above-mentioned inter-network mutual connecting system, when the node receives a message having common transmission destination address information and transmission source address information within a certain time interval, the node discards the message received later.
Japanese Laid-Open Patent Applications Nos. 3-162035, 6-37764 and 2003-157198 disclose related arts.